Cooling system for internal combustion engines



Sept. 13, 1938. G. KNocHENHAux-:R 2,129,846

I COOLING SYSTEM FOR INTERNALCOMBUSTION ENGINES Filed April 5, 1935 v2 Sheets-sheet 1 Sept. 13, 1938. G, KNOCHENHAUER COOLING SYSTEM FOR INTERNAL COMBUSTION ENGINES Filed April 5, 1935 2 Sheets-Sheet 2 W E N Patented Sept. .13, 1938 UNITED STATES PATENT `'ori-ICE COOLING SYSTEM FOR INTERNAL COMBUS- TION ENGINES Application April 5, 1935, Serial No. 14,731 In Germany April 9, 1934 15 Claims.

The present invention relates to cooling systems for internal combustion engines and has particular reference to systems of this character utilizing for the cooling medium a liquid the viscosity of which increases with decrease in temperature and vice versa.

Still more particularly the invention relates to cooling systems of the above character employing lubricating oil as the cooling medium.

The advantages of using lubricating oil as a cooling medium have already been recognized, but in order to successfully employ this liquid, or a liquid of like characteristics, it is necessary to utilize a cooling system having structural characteristics different from those suitable for a water cooling system. One of the principal reasons for this is that the specific heat of oil is much less than that ofwater. In order to make use of the viscosity characteristics of oil while at the same time avoiding the disadvantage of low specific heat, it has been proposed in the past to circulate the oil in a closed system under pressure in comparatively thin layers and at comparatively high speeds around the engine parts requiring cooling. Such circulation of the oil has been proposed in conjunction with the use of an air-cooled radiator through which the oil is circulated in series with the cooling jackets of the engine so as to dissipate the heat transmitted to the oil from the engine. In an arrangement of this sort, the viscosity characteristics of the cooling oil are utilized advantageously since the rate of cooling is automatically altered to compensate for Iluctuating temperatures. When the temperature of the system is high the rate of ilow of the oil and the cooling eiected by it are accelerated because of low oil viscosity, and in case of low temperatures the increased viscosity and resistance to iiow of the oil result in a lower rate of cooling. However, some difculty may be encountered with arrangements as heretofore proposed because of the fact that the outside air temperature may become so cold as to congeal the oil in the radiator, and in eiect freeze it. With the usual arrangement of the parts of the cooling system, this freezing of the radiator tends to stop oil circulation throughout the entire system. This has previously been recognized, and the difficulty has heretofore been overcome to a certain extent by providing a continuously open by-pass for the radiator so that when the latter is lled with congealed oil it may be shortcircuited until the heat carried to the radiator by the oil which flows through the engine cylinder jackets has an opportunity to thaw the (Cl. 12S- 174) radiator to an extent suillcient to permit circulation throughout the entire system to be established. 1

A continuously open by-pass of this character is, however, subject to the disadvantage that v5 it involves continuous loss of power in the cooling system due to flow of the cooling uid through the by-pass whether such flow is required or not, and this loss of power cannot bereduced to the desired extent by reducing to a very small area the cross-section of the by-pass, for the reason that with such small iiow area the by-pass is not effective for the purpose desired.

In order to eliminate the difficulties encountered with systems as heretofore suggested, it is proposed, in accordance with the present invention, to provide a novel arrangement of radiator, pumping means and engine jacket spaces, with respect to ow of cooling fluid, which will enable both the radiator and the jacket spaces to be exposed to both the full pressure of the delivery from the circulating pumping means, and the full suction eiect produced by such means. With such an arrangement, the force tending to produce circulation of oil through the jacket spaces of the engine is independent of the viscosity condition of the oil in the radiator, and suitable circulation of oil through the jacket spaces can be absolutely depended upon regardless of conditions of outside temperature. j

The invention may be carried into effect with different specific arrangements, of which the simplest consists of a single circulating pump which forces oil to the radiator and jacket spaces and which withdraws oil from them through circulating circuits arranged in parallel with respect to ow of oil toL and from the pumping means.

With an arrangement such as this, it is possible to obtain the desired automatic adjustment of the cooling effect under diierent temperature conditions. The reason for this is that the radiator and jacket spaces of the engine are continuouslyv subjected to like pump pressures and for this reason the speed of circulation of the oil through them is inversely proportional to the viscosity of the oil. 'I'his is not true of the old form of cooling system arrangements in which the radiator and jacket spaces are arranged in series with respect to ow of the cooling medium.

Further, with the engine jacket circuit and the radiator circuit arranged in parallel only about half of the pump delivery pressure is required to effect the desired circulation as compared with what would be required if a series arrangement of 55 the parts were employed. This is of substantial importance, since in systems of the kind under discussion a small and, comparatively slow speed centrifugal pump is the simplest and most desirable form of pumping element, and with this type of pump it is difllcult to get sumcient delivery pressure to effect the desired circulation of relatively viscous oil when it must be circulated in series through the jacket spaces and the radiator against a pressure representing the combined flow resistance of the two parts of the system.

For a better understanding of the detailed nature of the invention and the manner and advantages of its use, reference may best be had to the ensuing description of suitable embodiments of apparatus for carrying the invention into effect illustrated in the accompanying drawings forming a part of this specification.

In the drawings:

Fig, 1 is a more or less diagrammatic side elevation partly in section of an engine having a cooling system embodying the invention;

Fig. 2 is a central section on an enlarged scale vshowing another form of apparatus for carrying the invention into effect;

Fig. 3 is an end elevation of an engine adapted to have attached thereto apparatus of the kind shown in Fig. 2;

Fig. 4 is a more or less diagrammatic illustration of an engine having another form of cooling system embodying the invention; and

Fig. 5 is a view similar to Fig. 4 showing an engine with still another form of cooling system embodying the invention.

Referring now to Fig. l, reference character I0 designates an internal combustion engine having an oil cooling system which provides for forced circulation of the oil around the cylinder barrels and over the cylinder heads, around the valve seats and exhaust passages. 'Ihe specific details of construction of the jacket spaces forming the path of circulation of the oil are not essential to the present invention, and for purposes of illustration I have indicated the path of flow of the cooling oil through the Jacket spaces by the dotted lines I2 and I4 and branches I2a, the branch lines designated I2a indicating the path of flow around the individual cylinders. Advantageously the oil is circulated in jacket spaces providing for flow of oil in thin films at relatively high velocity, and the construction may be in accordance with the disclosure in application Serial No. 513,335 filed February 4, 1931, by Fredrik Ljungstrom, (matured into Patent No. 2,078,499, granted April 27, 1937).

At one end of the cylinder block there is mounted the circulating pump I6 for circulation of the cooling oil. This pump is advantageously in the form of a centrifugal pump of the type generally employed for producing circulation in cooling systems of this character, and is advantageously rigidly connected to the engine by means of the connections I8 and 20, which are connected respectively to the inlet 22 and the outlet 24 of the pump.

From the drawings it will be evident that the passages represented by lines I2, I2a and I4 in the cylinder block, the connections I6 and 2l, and the pump itself, form a closed circuit for circulation of cooling iluid through the pump and the jacket spaces of the engine.

Connections 26 and 26 provide support for a radiator indicated as a whole by reference number 30, which is advantageously in the form of a central casing 32 providing an inlet chamber 34 and an outlet chamber 36. Chamber 24 is connected by connection 26 to the outlet 24 of pump I6, and is also in communication at the outlet of the pump with connection 20 leading to the jacket spaces. Chamber 36 is connected by means of connection 26 to the inlet of the pump and is also in communication with the connectionl I8 leading from the engine jacket spaces. Chambers 34 and 26 are connected by a plurality of bent tubular cooling elements or tubes 26. The pump I6 and the fan 40 for forcing cooling air over Athe radiator tubes are advantageously mounted on a common shaft 42, which may be driven in the conventional manner by means of a belt drive 44 from the engine shaft 46.

Advantageously the general form of construction of the radiator may be in accordance with the disclosure in U. S. Patent No. 1,980,811 granted November 13, 1934, to Fredrik Ljungstrom.

The lines and arrows shown in the figure indicate the path of ilow from the pump through the radiator and back to the pump, and from the drawings it will be evident that the radiator, the connections 26 and 28 and the pump together form a second circuit for circulatory ilow of the cooling fluid, which circuit is in parallel with the circuit which includes the jacket spaces of the engine. It will further be observed that both of these circuits and the system constituted by the two of them are closed, so that the system may be maintained at a pressure above atmospheric if desired.

In the embodiment illustrated, lubricating oil of the same kind as is used for lubricating the moving parts of the engine is employed as the cooling fluid, and the cooling system is advantageously maintained in filled condition by means of lubricating oil taken from the engine sump 48 by the lubricating oil pump 50 which discharges into the passage 52. Passage 52 is in communication with the engine bearings and a branch 54 leads to the engine jacket spaces by way of a check valve 56. A pressure relief valve 5I is advantageously provided in order to prevent the possibility of excess pressure in the cooling system. and the pressure of the oil as delivered from the pump 5I) is advantageously limited by means of a spring-loaded pressure relief device 60.

'I'he structural details of structure suitable for the supply of oil to the cooling system and the circulation of oil through the jacket spaces are disclosed in application Serial No. 661,250 filed March 17, 1933 by Fredrik Ljungstrom, (matured into Patent No. 2,085,810, granted July 6, 1937).

The operation of the cooling system will be largely obvious from the drawings, since it is evident that the cooling oil discharged from pump I6 will have two possible paths of flow, one through the engine jacket circuit and the other through the radiator circuit. It will further be evident that both circuits are continuously subjected to the full pressure and suction eilects of the pump, and accordingly the relative rates of ilow through the two circuits will depend upon the relative viscosities of the cooling Aoil in the two circuits. If, for example, the engine isstarted when very cold, the relatively viscous oil in the radiator, producing high resistance to flow in the radiator circuit, will not interfere with the rapid establishment of circulation of cooling iluid in the jacket circuit. In the jacket circuit the relatively slow circulation when the engine is started permits the engine to rapidly warm up, thus minimizing condensation losses and other undesirable factors of operation of a cold engine. As soon as the engine warms up the viscosity of the uid in the jacket circuit is automatically lowered and the rate of circulation in this circuit increases with decreasing viscosity of the uid. Then gradually the heat generated by the engine serves to reduce the viscosity of the oil in the radiator circuit, and this circuit commences to function as required under normal engine operating conditions.

Due to the fact that the viscosity of the cooling fluid varies with variations in temperature,

it will be evident that during normal engine operation a. substantially automatic balance is obtained which results in the provision of cooling at a rate in accordance with the momentary requirements. If, for example, the outside air is very cold, the tendency will be for the oil to congeal at a relatively rapid rate in the radiator tubes, thus increasing the resistance to ilow and cutting down the rate of ow of oil in the radiator circuit. This in turn results in maintaining the temperature of the cooling oil in the jacket circuit at the desired value, and operation of the engine at an undesirably low temperature is avoided. With increase in the value of the outside air temperature, the viscosity of the oil in the radiator circuit is reduced, and the desired rapidity of cooling flow through this circuit is maintained. 'I'hese desirable features of operation flow substantially from the fact that both circuits are continuously subjected to substantially constant pump pressure and suction, each circuit being substantially unaffected with respect to pressures by variations in the resistance to ilow through the other of the circuits.

Turning now to Figs. 2 and 3, another embodiment of apparatus is illustrated in which the radiator casing 32a is connected to the inlet opening 62 and outlet opening 64 of the jacket space 66 of the engine Illa. In this embodiment the circulating pump is mounted within the radiator casing 32a and comprises a rotor Ilia mounted on shaft 42a and discharging through diifusor passages 68 to the chamber 18, which serves as the discharge chamber for the pump and the inlet chamber for the radiator tubes 38a. Casing 32a also provides a chamber 12 which serves as the outlet chamber for the tubes 38a and as the inlet chamber for the pump. Chamber 18 is connected with the engine inlet 62 by means of the connection 14, and outlet I64 from the engine is connected by means of connection 18 to the inlet of the pump.

As will be noted from the drawings an annular web 18 in casing 32a separates the passage provided by the connection 16 from the chamber 'l2 substantially up to the point of entrance of uid into the inlet end of the pump rotor Ilia.

'I'he pump rotor Ilia and the fan 49a are operated in this embodiment by means of a gear drive consisting of a gear 80 on shaft 42a, which gear is advantageously driven from the engine cam shaft gear 82.

The path of flow of the cooling oil in this embodiment of the apparatus has been indicated by lines and arrows which it will be observed dei-lne two separate circuits arranged in parallel with respect to ilow of cooling medium, as in the embodiment previously described. Oil discharged from the pump to the chamber 'I8 may flow through tubes 38a to the chamber 72 and from this chamber to the inlet of' the pump in a closed radiator circuit. Oil from the chamber 18 may also flow through the connection 14, the engine jacket spaces and the connection 16 back to the inlet of the pump, inside of the web 18 forming the second closed circuit constituting the jacket space circuit. By means of the construction provided at the inlet of the pump rotor and at the outlet from the rotor it will be evident that the fluid in the two circuits is at all times subjected 4to substantially the same pressure and suction means comprises two separate circulating pumps- 84 and 88. The outlet of the pump 88 is in communication by means of the connection 88 with the inlet of the jacket space of the engine, and the outlet of the jacket space is connected by means of connection 98 to the inlet of pump 88. The outlet of pump 8B is connected by means of connection 92 to the inlet of the radiator 38h, and the outlet of the radiator is connected by means of connection 94 to the inlet of the pump 8l. Connections 88 and 92 are placed in communication by the connection 96 in which is located valve 98, which is advantageously in the form of an ordinary buttery valve. Valve 98 may be operated manually or may be opened and closed under the inuence -ofa thermostatic engine control which has been indicated as comprising a thermostat |88 located in the jacket space of the engine and operating, by means of the bellows |82 to which it is connected, to move valve 98 toward closed position as the engine temperature increases and to move the valve toward open position as the engine temperature decreases.

'Ihe direction of the flow of cooling oil in this embodiment of the system has been indicated by means of lines and arrows, and from the character of the iiow as indicated by the arrows it will be evident thatas in the previously described embodiments the jacket space circuit and the radiator circuit are each continuously subjected to the full discharge pressure of the pumping means and also the full suction effect thereof. If the valve 98 is open and the radiator 38h is cold, so that there is high resistance to ow of oil therethrough, it will be evident that there is a jacket circuit comprising the engine jacket spaces,

vthe connections 90, 96 and 88 and the pump 86 through which oil may circulate until the radiator is sufciently warmed up to permit circulation through the radiator circuit, which may be said to comprise the radiator, pump 84, and connections 96, 92 and 94. As the engine temperature increases from a cold start, the valve 98 may be closed and with the valve closed it will be evident that the system will operate as a single circuitl system with the radiator and the jacket spaces connected in series with respect to iiow of cooling fluid. It may thus be said that this embodiment provides an arrangement including connections for selectively providing circuits arranged in parallel or in series with respect to flow of the cooling medium. In this connection it is to be observed, however, that regardless of whether valve 98 is open or closed,

or, in other words, regardless of whether the system'-.is operating with a single series circuit or two parallelly arranged circuits, the inlet to the radiator and the inlet to the jacket space of the engine are both subjected to full pump pressure and the outlets from the radiator and from the engine jacket space are continuously subjected to the full suction effect of the pumping means. y

Fig. illustrates a slightly different arrangement of the general type of system illustrated in Fig. 4. In this embodiment the arrangement of pumps, radiator, jacket spaces and connections is substantially like that previously described, but differs therefrom in that instead of the connections 88 and 92 being connected by the connection 96, as in Fig. 4, the connections 90 and 94 are connected by the connection |04. In connection |04 there is located a valve 98a controlled by the thermostat means |00, |02 in the manner previously described. As in Fig. 4, the direction cf flow of the oil is indicated by lines and arrows, and it will be evident that in this arrangement also there is provided the possibility of either two parallel circuits or a single series circuit for flow of the cooling oil. In both of the embodiments of Figs. 4 and 5, it is preferable that pumps 84 and 86 be alike with respect to operating characteristics and pressures produced, and under normal operating conditionsV substantially no flow of oil will take place through the cross connections 96 or |04, since with arrangements of this sort the flow areas should be so proportioned that the resistance to flow through the two circuits are substantially the same. With substantial variations of temperature there will be flow through these cross connections which may be in either one of two directions as indicated by the arrows, depending upon whether the temperature of the cooling air is increasing and the resistance to flow through the radiator decreasing, or the opposite. The balancing action produced by such iiow through the cross connections is inherent in the system, and in this connection it is to be pointed out that the valve control for these cross flow passages is not essential to the functioning of the apparatus, but is preferably employed to facilitate the securing of the best results from the operation of the system.

From the foregoing it will be evident that arrangements other than those shown by way of illustration may be employed for carrying the invention into effect, and the invention is accordingly to be understood as embracing all such forms of apparatus as may fall within the scope of the appended claims.

What I claim is:

l. In a closed circuit cooling system for internal combustion engines, pumping means for circulating cooling fluid through the system, means providing jacket space for circulation of the cooling fluid to cool the engine, a radiator, and connections for continuously subjecting both the jacket space and the radiator to both the direct pressure and direct suction effects of said pumping means.

2. In a closed cooling system for internal combustion engines, pumping means for circulating cooling uid through the system, means providing jacket space for circulation of the cooling fluid through the engine, a radiator, and connections between said pump, said jacket space and said radiator providing a rst circuit including the pump and the radiator only, and a second closed circuit including the pump and the jacket space only said circuits being arranged in parallel with respect to now of the cooling duid, whereby cooling fluid may flow through said second circuit without ilowing through said first circuit.

3. In a closed cooling system for internal combustion engines, pumping means, means providing jacket space for circulation of cooling fluid through the engine, said jacket space having an inlet and an outlet, a radiator having an inlet and an outlet, and connections providing for circulatory flow of cooling fluid between said pumping means, said radiator and said jacket space including connections establishing direct communication between the discharge and suction sides of said pumping means and said inlets and said outlets respectively.

4. In a closed cooling system for internal combustion engines, a pump, means providing jacket space for circulation of cooling fluid through the engine, said jacket space having an inlet and an outlet, a radiator having an inlet and an outlet, a connection providing direct communication between the outlet of said pump and the inlet of said jacket space, a connection providing direct communication between the outlet of said pump and the inlet of said radiator, a connection providing direct communication between the outlet of said jacket space and the inlet of said pump, and a connection providing direct communication between the outlet of said radiator and the inlet of said pump.

5. In a closed cooling system for internal combustion engines, a pump having an inlet and an outlet, means providing jacket space for circulation of cooling fluid through the engine, said jacket space having an inlet and an outlet, a radiator having an inlet and an outlet, a connection providing direct communication between the outlet of said pump and the inlet of said jacket space, a connection providing direct communication between the outlet of said pump and the inlet of said radiator, a connection providing direct communication between the outlet of said jacket space and the inlet of said pump, and a connection providing direct communication between the outlet of said radiator and the inlet of said pump, the two last mentioned connections having separate outlets located closely adjacent to the inlet of the pumping element of the pump.

6. In a closed cooling system for internal combustion engines of the type in which oil is adapted to be circulated under pressure, a centrifugal Dump, a radiator having an inlet and an outlet, means providing jacket space for the engine, said jacket space having an inlet and an outlet, connections for delivering oil from the, pump directly to both of said inlets, and connections for drawing oil directly from both of said outlets to the inlet of the pump.

7. In a closed cooling system for internal combustion engines, pumping means, a radiator, means providing jacket space for the engine, and connections providing communication between said pump, said radiator and said jacket space whereby forced circulation of the cooling fluid due to pump pressure may be effected in the system in two separate circuits ilowing in parallel with respect to each other or in a single circuit including said radiator and said jacket space in series.

8. In a closed cooling system for internal combustion engines, a first pump, a second pump, a radiator having an inlet and an outlet, means providing jacket space for the engine, said jacket space having an inlet and an outlet, a connection providing direct communication between vthe inlet of said rst pump and the outlet of said jacket space, a connection providing direct communication between the inlet of said second pump and the outlet of said radiator, a connection providing direct communication between the outlet of said rst pump and the inlet ofA said radiator, a connection providing direct communication between the outlet oi said second pump and the inlet of said jacket space, and a balancing connection providing a direct communication between the inlet of said jacket space and the inlet of said radiator.

9. In a closed cooling system for internal combustion engines, a rst pump, a second pump, a radiator having an inlet and an outlet, means providing jacket space for the engine, said jacket space having an inlet and an outlet, a connection providing direct communication between the inlet of said rst pump and the outlet of said jacket space, a connection providing direct communication between the inlet of said second pump and the outlet of said radiator, a connection providing direct communication between the outlet of said rst pump and the inlet of said radiator, a connection providing direct communication between the outlet of said second pump and the inlet of said jacket space, a balancing connection providing a direct communication between the inlet of said jacket space and the inlet of said radiator. and a control valve for controlling iiow through said balancing connection.

10. In a closed cooling system for internal combustion engines, a rst pump, a second pump, a radiator having an inlet and an outlet, means providing jacket space for the engine, said jacket space having an inlet and an outlet, a connection providing direct communication between the inlet of said rst pump and the outlet oi' said jacket space, a connection providing direct communication between the inlet of said second pump and the outlet of said radiator, a connection providing direct communication between the outlet of said rst pump and the inlet of said radiator, a connection providing direct communication between the outlet of said second pump and the inlet of said jacket space, a balancing connection providing direct communication between the inlet of said jacket space and the inlet of said radiator, a control valve for controlling flow through said balancing connection, and means responsive to the temperature of the heatedA cooling iluid in the system for regulating the position of said controlling means.

11. In a closed cooling system for internal combustion engines, a first pump, a second pump, a

radiator having an inlet and an outlet, means4 providing jacket space for the engine, said jacket space having an inlet and an outlet, a connection providing direct communication between the inlet ofr said Iirst pump and the outlet of said jacket space, a connection providing direct communication between the inlet of said second pump and the outlet oi' said radiator, a connection providing direct communication between the outlet of said flrst pump and the inlet of said radiator,

a connection providing direct communication between the outlet of said second pump and the inlet of said jacket space, and a balancing connection providing direct communication between the outlet of said radiator and the outlet of said jacket space.

12. In a closed cooling system for internal combustion engines. a iirst pump, a second pump, a

` radiator having an inlet and an outlet, means providing jacket space for the engine,said jacket space having an inlet and an outlet/a connection providing direct communication between the inlet of said rst pump and the outlet of said jacket space,a connection providing direct communication between the inlet of said second pump and the outlet of said radiator, a connection providing direct communication between the outlet of said iirst pump and the inlet of said radiator, a connection providing direct communication between the outlet of said second pump and the inlet oi said jacket space, a balancing connection providing direct communication between the outlet of said radiator and the outlet of said jacket space, and a control valve for controlling flow through said balancing connection.

13. In a closed cooling system for internal combustion engines, a first pump, a second pump, a radiator having an inlet and an outlet, means providing jacket space for the engine, said jacket space having an inlet and an outlet, a connection providing direct communication between the inlet of said iirst pump and the outlet of said jacket space, a connection providing direct communication between the inlet of said second pump and the outlet of said radiator, a connection providing direct communication between the outlet of said iirst pump and the inlet of said radiator, a connection providing direct communication between the outlet oi said second pump and the inlet of said jacket space, a balancing connection providing direct communication between the outlet of said radiator and the outlet of said jacket space, a control valve for controlling ow through said balancing connection, and means responsive to the temperature of the heated cooling iiuid in the system for regulating the position of said controlling means.

14. That improvement in the art of cooling internal combustion engines which consists in simultaneously circulating a portion of the cooling iiuid in a first closed circuit including the jacket space of the engine and subjecting another portion of the cooling uid to a positive pressure tending to produce forced circulation in a second closed circuit including a cooling radiator.

15. That improvement in the art of cooling internalv combustion engines with the aid of a circulating pump which consists in continuously subjecting the jacket space of the engine to be cooled to the direct pressure and suction effect of the `circulating pump and continuously subjecting the radiator for cooling the cooling fluid to the direct pressure and suction effect of the circulating pump.

GNTHER KNOCHENHAUER. 55 

